Transformers which are needed for power converters, e.g., rectifiers or inverters, each have a plurality of windings which include a low-voltage winding and a high-voltage winding and which are used to transform the respective two-phase or three-phase AC voltage to the desired voltage level.
A current which has been rectified in this manner regularly has residual ripple, that is to say a still remaining AC voltage component of a smoothed or regulated supply voltage after the latter has been rectified by a rectifier and smoothed by a capacitor and/or has been reduced to a lower level by a voltage regulator.
In order to reduce this residual ripple further, 12-phase, 18-phase and 24-phase rectifier circuits are often used. As a result, it is often possible to entirely dispense with a smoothing capacitor. Another advantage is the virtually sinusoidal input current and the resultant low mains/transformer load with distortive reactive power. The transformer which is more complicated to wind and secondarily has a delta winding and a star winding each with the same pole voltage is disadvantageous. This arrangement results in a phase shift of 30° with 12 phases. For a phase shift of 20° with 18 phases or 15° with 24 phases, two adjacent phases must be correspondingly added, as a result of which the required transformer becomes even more complicated, since one complete winding, that is to say a low-voltage winding and a high-voltage winding, with a separate outgoing line is respectively required for each phase.
If such windings are arranged beside one another on a common limb, a sufficiently large intermediate space, which is accordingly needed space for the required insulated routing-out of the winding conductors, needs to be provided between the windings which are arranged beside one another. This results in a corresponding spatial extent of these transformers combined with a corresponding space requirement.
However, the space required thereby is often not available, which either results in considerable space problems or allows only simpler circuit variants which are associated with the disadvantage of undesirable residual ripple, that is to say remnants of AC voltage.
On the basis of the known techniques described above, exemplary embodiments of the present disclosure provide a transformer of the type mentioned at the outset, which transformer allows better use of space by means of technical measures and thus allows the largest possible number of windings to be arranged with the smallest possible physical volume.